commit 1f363b764f2c072e692e1747e8044326e37fe590
author Nick Vatamaniuc <vatamane@gmail.com> Tue May 23 11:24:12 2023 -0400
committer Nick Vatamaniuc <nickva@users.noreply.github.com> Tue May 23 12:11:28 2023 -0400
tree 375802c7e2bc09d85f3076f1e493f706ff319e89
parent a4bad8d8e93eaa93a56465a082524f18fd736178

Improve fsync metrics time calculation

Since we're using fractional milliseconds, might as well measure at the
nanosecond resolution.

```
 rp(couch_stats:sample([fsync,time])).
[{min,19.572592},
 {max,41.60692},
 {arithmetic_mean,22.214490860169498},
 {geometric_mean,22.134517662321407},
 {harmonic_mean,22.068093005211708},
 {median,22.147823},
 {variance,4.5064974888058495},
 {standard_deviation,2.1228512639386325},
 {skewness,5.243648789818805},
 {kurtosis,43.072222638582026},
 {percentile,[{50,22.147823},
              {75,23.18369},
              {90,23.573497},
              {95,23.780686},
              {99,27.245643},
              {999,41.60692}]},
 {histogram,[{20.572592,24},
             {21.572592,68},
             {22.572592,51},
             {23.572592,68},
             {24.572592,19},
             {25.572592,3},
             {26.572592,0},
             {27.572592,1},
             {28.572592,0},
             {29.572592,0},
             {30.572592,0},
             {31.572592,0},
             {32.572592,0},
             {33.572592,0},
             {34.572592,0},
             {35.572592,0},
             {36.572592,0},
             {37.572592,0},
             {38.572592,0},
             {39.572592,1},
             {40.572592,0},
             {41.572592,0},
             {42.572592,1}]},
 {n,236}]
ok
```